1. Technical Field
The technical field relates to an integrated device having a metal oxide semiconductor field effect transistor (MOSFET) cell array embedded with a junction barrier Schottky (JBS) diode.
2. Background
In order to achieve standards of low carbon emission and high energy efficiency, power devices are more and more important in electronic products and power supply systems. In the green energy industries, such as electric vehicle (EV)/hybrid electric vehicle (HEV) industries, distributed power and smart grid industries, and wind power and photo voltaic (PV) system industries, power consuming and energy conversion efficiency of devices are critical in power saving. The Si-based devices (e.g. Si-SBD, Si-MOSFET, Si-IGBT etc.) are adopted in these applications. However, such devices have high thermal resistivity and thus heat dissipation becomes a problem. The heat sink modules of such devices occupy a relatively large space in the systems. Moreover, such devices have poor turn-on and high switching energy loss.
Since wide-band-gap materials such as silicon carbide (SiC) have high thermal conductivity which is three times the thermal conductivity of silicon, the wide-band-gap materials can be operated normally in a higher temperature condition and are beneficial to the compact systematization of heat sink modules. In addition, SiC has a high withstand voltage and a high critical breakdown field, and a withstand voltage layer can have a higher concentration and a smaller thickness in the devices, such that the devices using SiC have lower resistance and therefore lower turn-on loss. Moreover, because the intrinsic carrier concentration (Ni) of SiC is lower than that of Si, SiC has a lower current leakage characteristic and a short response time almost near zero, and thus, lower switching loss is generated. Generally, half power consumption of the power system can be effectively saved when SiC devices replace Si devices.
In the key motor drivers of EV/HEV for medium-to-high power applications, and in the key PV inverters of PV/smart grid for high power applications, MOS transistor switches and diode devices such as Schottky barrier diodes (SBD) or junction barrier Schottky diodes (JBS) are provided in their power modules. These devices have voltage ratings from 600V, 1,200V to 1,700V. In the market, a hybrid module combining Si-IGBT and SiC-diode replaces the traditional module only containing Si devices, so as to reduce the power consumption and decrease the volume of the whole module. However, in the said hybrid module, Si-IGBT is a bipolar switching device, in which higher switching power loss occurs because the reverse recovery current thereof cannot quickly dissipate. Therefore, a SiC device is required to replace the key Si-IGBT. The most feasible device is SiC-MOSFET, which can be categories into a lateral channel structure referred to as SiC-DMOSFET and a vertical channel structure referred to as SiC-UMOSFET. SiC-MOSFET is a majority carrier switching device having a quick switching speed. In the conventional fabricating method of such power module, MOSFET and SBD (or MOSFET and JBS) are fabricated on separate chips and then packaged together, in which many wirings are required and the stray inductance is accordingly increased. Moreover, with such conventional method, greater space and therefore higher production cost are required.